Gear machine with axially movable end wall seal

ABSTRACT

A fluid machine has a high pressure side and a low pressure side and accommodates in a chamber of its housing a pair of meshing gears which are mounted for rotation about axially parallel shafts. A plurality of shaft-journalling sleeves are provided, each associated with one of the shafts and each having one axial end face directed towards an associated gear for sealing engagement with the same and another axial end face directed away from the gear and towards one of two end walls bounding the chamber. Some or all of these sleeves are provided in their axial end faces which face away from the respective gear with recesses having substantially the contour of a numeral three the open side of which faces the low-pressure side of the fluid machine. It is these last-mentioned sleeves which have limited freedom of axial movement relative to the associated gear. A sealing element is accommodated in and corresponds to the contour of each of these recesses, having free end portions which extend to the circumferential wall bounding the chamber. A small pressure space is formed adjacent each of these free end portions intermediate the same and the associated recess and is in communication with the high-pressure side of the fluid machine.

.1 ited States Dworak et al.

5 atent 1 1 1 1 GEAR MACHINE WITH AXIALLY MOVABLE END WALL SEAL [75] Inventors: Wilhelm Dworak, Stuttgart; Claus Jo'ns, Munich; .lan Vlemmings. Hochdorf. all of Germany [73] Assignee: Robert Bosch G.m.b.H., Stuttgart.

Germany [22] Filed: Feb. 4, 1974 [21] Applv No: 439,020

[30] Foreign Application Priority Data Mar. 6. 1973 Germany 7308439IU1 [52] U.S. Cl. 418/132 [51] llnt. Cl...... F01c 19/08; F03c 3/00; F04c 15/00 [58] Field ofSearch ..4l8/l3l. 132

[5 6] References Cited UNITED STATES PATENTS 3.137.238 6/1964 Gordon 418/132 3.348.492 10/1967 Olson et al 418/131 3.371.615 3/1968 Pettyjohn et al.. 418/132 3.473.476 10/1969 Davidson 418/132 3.539.282 11/1970 Forschner 418/132 Primary Examiner-John J. Vrablik Attorney. Agent. or FirmMichael S. Striker [57] ABSTRACT A fluid machine has a high pressure side and a low pressure side and accommodates in a chamber of its housing a pair of meshing gears which are mounted for rotation about axially parallel shafts. A plurality of shaft-journalling sleeves are provided, each associated with one of the shafts and each having one axial end face directed towards an associated gear for sealing engagement with the same and another axial end face directed away from the gear and towards one of two end walls bounding the chamber. Some or all of these sleeves are provided in their axial end faces which face away from the respective gear with recesses having substantially the contour of a numeral three the open side of which faces the low-pressure side of the fluid machine. It is these last-mentioned sleeves which have limited freedom of axial movement relative to the associated gear. A sealing element is accommodated in and corresponds to the contour of each of these recesses, having free end portions which extend to the circumferential wall bounding the chamber. A small pressure space is formed adjacent each of these free end portions intermediate the same and the associated recess and is in communication with the highpressure side of the fluid machine.

10 Claims, 5 Drawing Figures PATENTEDJUN24 ms 3, 89 1, 366

sum 1 HM mum H limlu PATENTEDJUN24 ms 913 0 SHEET 3 Fig.4 Fig-5 GEAR MACHINE WITI-I AXIALLY MOVABLE WALL SEAL BACKGROUND OF THE INVENTION END nally meshing gears the shafts of which are mounted at least at one axial side of the respective gear in bores of journalling meambers. usually journalling sleeves. of which at least the journalling members at one axial side of the gears have limited freedom of axial movement toward and away from the associated gear. At the side of the thus movable journalling members which faces away from the respective gear, the journalling members are formed with seals which delimit two differential pressure fields. that is a higher and a lower pressure field, and it is the pressure of these fields which presses the movable journalling members against the associated gears.

In one prior-art construction of this type, the seal is accommodated in a groove formed in a cover of the housing. which cover is of cast iron or steel. The groove must be milled in the cover. an operation which is evidently labor-intensive in terms of the operations required for the milling, and capital-intensive in terms of the equipment needed.

SUMMARY OF THE INVENTION It is an object of the present invention to further improve a fluid machine of the type under discussion so as to overcome the disadvantages of the prior art.

More particularly. it is an object of the present invention to provide an improved fluid machine of the type in question which can be produced more readily and at less expense than what is known from the prior art.

An additional object of the invention resides in such a fluid machine which. despite the improvements obtained. will nevertheless afford an effective seal for delimiting the differential pressure field.

In keeping with the above objects. and with others which will become apparent hereafter, one feature of the invention resides. in a fluid machine having a high pressure side and a low pressure side. in a combination comprising a housing having a chamber which is bounded by a circumferential wall and two opposite end walls. A pair of meahing gears is mounted in this chamber for rotation about axially parallel shafts. and these gears each have two opposite axial ends. A plurality of shaft-journalling members is provided. each associated with one ofthe shafts, and each having one axial end face directed towards the associated gear for sealing engagement therewith and an other axial end face directed to one of said end walls and away from the associated gear. At least some selected ones of the journalling members have limited freedom of axial movement relative to the associated gear.

According to the invention, a recess is formed in each of the other axial end faces of the selected journalling members and has substantially the contour of a numeral three the open side of which faces the lowpressure side. A sealing element is accommodated in and corresponds to the contour ofeach of the recesses, and each of these sealing elements has free end portions extending to the circumferential wall bounding the chamber. A small pressure space is formed adjacent each of these free end portions intermediate the same and the associated recess and is in communication with the high-pressure side of the fluid machine.

The sealing elements separate two pressure fields from one another. namely a high pressure field which is in communication with the lhigh pressure side of the fluid machine. and a low pressure field which is in communication with the low pressure side of the machine. The pressure in the high pressure field presses the axially movable journalling members into sealing engagement with the respectively associated gears and the axial ends thereof. If in such a fluid machine shaftjournalling members'of aluminum are used, then the recesses for the sealing elements can be readily formed during pressure casting of the shaft-journalling members. thus avoiding any need for a separate operation -such as a milling stepwhich was previously required to form the recesses.

The arrangement of the recesses and sealing ele ments in the machine according to the present invention has a further advantage. namely it provides for a particularly effective separation of the high pressure field and the low pressure field from one another. because the outer parts of the free arms or end portions of the respective sealing elements are pressedradially outwardly due to fluid pressure against the circumferential wall bounding the chamber.

The novel features which are considered a characteristic for the invention are set forth'in particular in the appended claims. The invention itself. however. both as to its construction and its method of operation, together with additional objects and advantages thereof. will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section through a fluid machine according to the present invention;

FIG. 2 is a section taken on line IIII of FIG. 1;

FIG. 3 is a section taken on line III-III of FIG. 1;

FIG. 4 is a plan view of one of the seals used in FIGS. I-3; and

FIG. 5 is a plan view of a supporting member used in conjunction with the seals in FIGS. l3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring firstly to FIGS. 1-3 it will be noted that the fluid machine illustrated therein which may be oper ated a pump or as a fluid motorhas a housing 10 which is formed with a chamber 1] having a cross sec tion which approximately resembles a figure eight (compare FIGS. 2 and 3). The opposite axial ends of the chamber 11 are closed by covers or end walls I2, 13 (see FIG. 1) which are connected with the housing 10 in suitable manner, for instance by means of nonillustrated bolts or the like.

A pair of exteriorly meshing gears l4, 15 is mounted in the chamber 1], being mounted on shafts 16, 17 each of which extends through one of the halves of the chamber 11. The shafts l6 and 17 extend in axial parallelism with one another and are journalled in bores of journalling members, here illustrated as shaftjournalling sleeves 182l, respectively. Advantageously, but not necessarily. the sleeves l821 will be of aluminum. FIG. 1 shows that the sleeves I8 and 19 are associated with the gear 14, whereas the sleeves 20, 21 are associated with the gear 15.

The sleeves each have axial end faces which face away from the rcspsectively associated gears and which are flush with the plane of the end faces of the housing 10. The cover 13 is provided with a bore 22 through which a drive shaft 23 extends from the gear towards the outside of the housing 10. A sealing ring 24 is provided in the bore 22, to seal the shaft 23 with respect to the cover 13, and thus to seal the interior of the chamber 11 with respect to the exterior of the housing 10.

The configuration of the sleeves 18-21 is accommodated to the cross-sectional configuration of the housing 11, i.e. they are cylindrical and are each provided with a flat facet, such facets being in abutment with one another (see FIG. 1). An inlet bore 25 communicates with the chamber 11 at the level of the gears 14, 15. In the same axial direction and also at the level of the gears '14, 15 there is provided an outlet bore 26 which extends from the chamber 11 to the exterior of the housing.

As FIGS. 1 and 3 show particularly clearly, the axial end faces of the sleeves 18-21 which face away from the respectively associated gears 14, 15 are provided with recesses 27, 28. The recesses of two adjacent ones of the sleeves, i.e. in the sleeves 18 and 20 and in the sleeves l9 and 21, merge with one another to form a contionous recess. The recess 27 accommodates a sealing element 29, and the recess 28 accommodates a similar sealing element 30. Both of these sealing elements have a contour which approximately resembles a numeral 3, as clearly shown in the plan view of FIG. 4. The curved portions of the respective sealing elements surround the associated shafts with slight spacing, whereas the free end portions of the sealing elements extend to the inner surface of the circumferential wall bounding the chamber 11, in the direction towards the inlet side of the machine.

The free end portions of the sealing elements, of which the sealing element 29 is shown by way of example in FIG. 4, the sealing element 30 being identical therewith, are formed with nose-like projections 29'. 29 in the case of the sealing element 29. These projections are located in radially outwardly extending terminal portions or zones of the respective recesses 27, 28, zones which are designated with reference numerals 27' and 27" with respect to the recess 27 which is visible in FIG. 3. These zones 27' and 27" are not quite as wide the projections 29', 29", so that the latter are received in these zones under a slight amount of compression. Intermediate each of the projections 29', 29" and the associated recess (the recess 27 in the case of the sealing element 29) there is formed a small free pressure space which is visible in FIG. 3 with respect to the sealing element 29 and is there designated with ref erence numerals 31 and 32, respectively. These pressure spaces 31, 32 are in communication with the high pressure side of the fluid machine.

The sealing elements 29, 30 separate -at the axial ends of the sleeves which face away from the respective gears 14, 15 two differential pressure fields from one another. At the side at which the sealing element 29 is located, these pressure fields are designated with reference numerals 33 and 34 (compare FIG. 3), and it will be seen that the pressure field 33 the high pressure fieldis in communication with the high-pressure side of the fluid machine via a triangular housing recess 35. The pressure field 34 the low pressure lield is in communication with the low pressure side of the fluid machine via a similar triangular housing recess 36.

The scaling elements 29 and 30 are ofa material having clastomeric properties, for instance synthetic or natural rubber, or synthetic plastic material. It is desirable to protect them from excessive deformation under the influence of the pressure existing in the pressure fields 34, 35, because this could lead to damage. For this purpose each sealing element 29, 30 is associated with a supporting member 37, 38, respectively. These supporting members are advantageously of a synthetic plastic material, for example polyamide which has been found suitable for this purpose. One of the supporting members, namely the one designated with reference numeral 37, is illustrated in a plan view in FIG. 5 by way of example, the member 38 being identical with it. The supporting members are each located at that side of the respective sealing element which is directed towards the low pressure field 34. Respective seals 40, 41 are provided at the opposite end faces of the housing 10 and engage the covers 12, 13, respectively, to seal the interior of the chamber with respect to the ambient atmosphere.

FIG. 1 shows that the axial end faces of the sleeves 1821 which face the respective covers 12, 13, are formed at the outer circumference with inclined recesses which form a continuous configuration on the respectively adjacent sleeves 18 and 20, and 19 and 21. These recesses are designated with reference numeral 42 for the sleeves 18 and 20, and with reference numeral 43 for the sleeves 19 and 21; they terminate just short of the terminal zones of the recesses 27, 28.

In operation of the novel fluid machine, assuming that it acts as a pump, the gears 14, 15 will draw pressure fluid in known manner into the chamber 11 through the inlet bore 25, and will expel it through the outlet bore 26 to a non-illustrated user. The suction in the inlet bore 25 is transmitted via the recess 36 into the pressure field 34 which thus is at low pressure. The pressure in the outlet bore 26 is transmitted via the recess 35 to the pressure field 33, radially outwardly of the sealing elements 29, 30 so that high pressure exists in this region and presses the respective sleeves 18-21 into sealing engagement with the associated axial end faces of the gears 14, 15. The high pressure is also transmitted into the pressure spaces 31, 32 which causes the projections 29, 29", 30, 30 of the sealing elements 29, 30 to be pressed radially outwardly against the inner suface of the cireumerential wall bounding the chamber 11. This assures that no pressure fluid can flow from the high pressure field 33 into the low pressure field 34. The recesses 42, 43 which are formed bevels cause a rapid pressure increase in the high pressure field 33, in that they assured that this pressure field cannot receive pressure fluid at a time different from the pressure increase in the pumping chambers defined by the cooperating gear teeth of the gears 14, 15.

It is thus clear that the fluid machine according to the present invention avoids the disadvantages of the prior art and affords advantages commensurate with the purposes of the present invention, making it possible to construct the novel fluid machine more simply and at less expense than what is known from the prior art, and

also assuring that a more reliable separation ofthe high pressure field and low pressure field from one another is obtained.

It will be understood that each of the elements described above. or two or more together. may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a fluid machine. it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit ofthe present invention.

Withour further analysis. the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that. from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. ln a fluid machine having a high pressure side and a low pressure side, a combination comprising a housing having a chamber which is bounded by a circumferential wall and two opposite end walls; a pair of meshi'ng gears mounted in said chamber for rotation about axially parallel shafts, said gears each having two opposite axail ends; a plurality of shaft-journalling members. each associated with one of said shafts and each having one axial end face directed towards the associated gear for sealing engagement therewith and an other axial end face directed towards one of said end walls and away from the associated gear, at least some selected ones of said journalling members having limited freedom of axial movement relative to the associated gear; a recess formed in each of said other axial end faces of said selected journalling members and having substantially the contour of a numeral three the open side of which communicates with said low-pressure side; a pair of sealing elements accommodated in and correspondihg to the contour of each of said recesses. each sealing element having free end portions having a nose-like projection and extending to said circumferential wall; and a small pressure space formed gradually adjacent and behind each of said free end portions intermediate 6 the same and the associated recess and being in communication with said high-pressure side so that the pressure of fluid from said high-pressure side will constitute a force to urge said nose-like projections against said circumferential wall and thereby seal said chamher.

2. A combination as defined in claim I wherein said journalling members are journalling sleeves.

3. A combination as defined in claim 1. wherein said free end portions of said sealing elements extend substantially radially of said gears.

4. A combination defined in claim 1 wherein all of said other axial end faces are formed with said recesses. and wherein one of said sealing elements is located in each of said recesses and said pressure spaces are formed adjacent each of said free end portions of all of said sealing elements.

5. A combination as defined in claim 1, wherein said recesses are of substantially right-angular crosssectional configuration.

6. A combination as defined in claim 1, wherein said sealing elements are of a material having elastomeric properties.

7. A combination as defined in claim 1, wherein said other axial end faces of said jiournalling members are also formed with respective additional recesses located radially outwardly and slightly spaced from the respective first-mentioned recess and extending along the same, each of said additional recesses being in communieation with said high-pressure side and extending to said circumferential wall and having respective ends located closely adjacent to said free end portions of the respectively associated sealing element, so as to assure a rapid pressure increase acting upon said sealing elements.

8. A combination defined in claim 7, wherein said additional recesses are bounded by a bevelled surface.

9. A combination as defined in claim 1, said sealing elements each having a side directed towards a lowpressure field formed in said chamber; and further comprising supporting members of synthetic plastic material. each associated with one of said sealing elements for supporting the same against deformation and being located at said side of the respective sealing element which is directed towards said low-pressure field.

10. A combination as defined in claim 9, wherein said supporting members are of polyamide. 

1. In a fluid machine having a high pressure side and a low pressure side, a combination comprising a housing having a chamber which is bounded by a circumferential wall and two opposite end walls; a pair of meshing gears mounted in said chamber for rotation about axially parallel shafts, said gears each having two opposite axail ends; a plurality of shaftjournalling members, each associated with one of said shafts and each having one axial end face directed towards the associated gear for sealing engagement therewith and an other axial end face directed towards one of said end walls and away from the associated gear, at least some selected ones of said journalling members having limited freedom of axial movement relative to the associated gear; a recess formed in each of said other axial end faces of said selected journalling members and having substantially the contour of a numeral three the open side of which communicates with said low-pressure side; a pair of sealing elements accommodated in and corresponding to the contour of each of said recesses, each sealing element having free end portions having a nose-like projection and extending to said circumferential wall; and a small pressure space formed gradually adjacent and behind each of said free end portions intermediate the same and the associated recess and being in communication with said high-pressure side so that the pressure of fluid from said high-pressure side will constitute a force to urge said nose-like projections against said circumferential wall and thereby seal said chamber.
 2. A combination as defined in claim 1 wherein said journalling members are journalling sleeves.
 3. A combination as defined in claim 1, wherein said free end portions of said sealing elements extend substantially radially of said gears.
 4. A combination as defined in claim 1 wherein all of said other axial end faces are formed with said recesses, and wherein one of said sealing elements is located in each of said recesses and said pressure spaces are formed adjacent each of said free end portions of all of said sealing elements.
 5. A combination as defined in claim 1, wherein said recesses are of substantially right-angular cross-sectional configuration.
 6. A combination as defined in claim 1, wherein said sealing elements are of a material having elastomeric properties.
 7. A combination as defined in claim 1, wherein said other axial end faces of said journalling members are also formed with respective additional recesses located radially outwardly and slightly spaced from the respective first-mentioned recess and extending along the same, each of said additional recesses being in communication with said high-pressure side and extending to said circumferential wall and having respective ends located closely adjacent to said free end portions of the respectively associated sealing element, so as to assure a rapid pressure increase acting upon said sealing elements.
 8. A combination as defined in claim 7, wherein said additional recesses are bounded by a bevelled surface.
 9. A combination as defined in claim 1, said sealing elements each having a side directed towards a low-pressUre field formed in said chamber; and further comprising supporting members of synthetic plastic material, each associated with one of said sealing elements for supporting the same against deformation and being located at said side of the respective sealing element which is directed towards said low-pressure field.
 10. A combination as defined in claim 9, wherein said supporting members are of polyamide. 